1. Field of the Invention
The present invention relates to a colored filter mounted in a xenon lamp or a halogen lamp, used for automobile lighting.
2. Description of the Related Art
A conventional xenon lamp or a halogen lamp, used for automobile lighting, emits bluish white light immediately after being energized, however, there has been seen a tendency of a color temperature of the light to come down, turning a color thereof into yellow.
Further, it is possible to raise the color temperature by changing composition of a gas used in the lamps, but then there has arisen a problem that the color of the light becomes too bluish, resulting in failure to pass a compulsory automobile inspection.
It is therefore an object of the invention to provide a colored filter which can be easily mounted in a xenon lamp or a halogen lamp, used for automobile lighting, and a method of fabricating the same.
A pigment together with a binder used to be directly applied to a glass tube 11 of a conventional xenon lamp or halogen lamp. Because intense ultraviolet radiation and heat are contained in the xenon lamp or the halogen lamp, the binder has undergone degradation, causing the pigment to peel off the surface of the glass tube 11, and to adhere to a reflecting mirror, and so forth, of these lamps, thereby doing aesthetic harm to the lamps.
The invention provides a colored filter capable of emitting stable and bluish white light without causing a pigment to peel off even after use for many hours, and of being easily mounted in a xenon lamp or a halogen lamp, and a method of manufacturing the same.
A typical example of the colored filter easily mounted in the xenon lamp or the halogen lamp used for automobile lighting, according to the invention, is shown in FIG. 1.
The colored filter 2 is usually made of Pyrex glass or quartz glass, and it can be said that any material transparent and resistant to high temperature at not less than 600xc2x0 C. is suitable for use in the colored filter 2.
The colored filter 2 comprises a transparent cylindrical body 21 provided with a slit 22, and the inner surface 23 of the transparent cylindrical body 21 is coated with a pigment.
The invention has another feature in that the inner surface 23 of the transparent cylindrical body 21 is coated with the pigment for coloring by use of a flux only without using a binder.
As a coating method applicable to the invention, there can be cited the dipping coat method and the spin coater method, however, the inner surface of the transparent cylindrical body is preferably coated with a coloring composition composed of a pigment and a flux by use of the spin coater method while rotating the transparent cylindrical body around the axis thereof.
More specifically, the invention provides the following.
(1) A colored filter for use in a xenon lamp or a halogen lamp, wherein the inner surface of a transparent cylindrical body is coated with only a pigment by baking.
(2) A colored filter for use in a xenon lamp or a halogen lamp as set forth under the item (1) above, wherein the transparent cylindrical body is fitted onto the outer periphery of a glass tube of the xenon lamp or the halogen lamp.
(3) A colored filter for use in a xenon lamp or a halogen lamp as set forth under the item (2) above, wherein the transparent cylindrical body is provided with a slit defined across a full length of the transparent cylindrical body in the direction of length thereof.
(4) A colored filter for use in a xenon lamp or a halogen lamp as set forth under the item (3) above, wherein a spring is provided between the transparent cylindrical body and a seat.
(5) A colored filter for use in a xenon lamp or a halogen lamp as set forth under any one of the items (1) to (3) above, wherein the pigment is of one color or not less than two colors, selected from the group consisting of blue color, yellow color, red color, green color, and violet color.
(6) A method of fabricating a colored filter for use in a xenon lamp or a halogen lamp, said method comprising steps of:
dropping a coloring composition composed of only a pigment and a flux in the interior of a transparent cylindrical body while rotating the transparent cylindrical body around the axis thereof;
uniformly coating the inner surface of the transparent cylindrical body with the coloring composition; and
drying a uniform film of the coloring composition as formed before baking by heating.